Patent DE-102013002471-A1 (DE)
Title: In-situ determination of current melt level during directional solidification of partially molten material, comprises e.g. determining first melt height of melted material and producing shadow on molten surface of melted material
Inventor: FRIEDRICH JOCHEN
IPC: C30B11/02
Filed: 2013-02-13
Abstract: In-situ determination of the current melt level during directional solidification of partially molten material, comprises (a) determining first melt height (z0) of melted material at a first time point (t0), (b) producing a shadow on the molten surface of melted material at first time point (t0), (c) determining the first position (x0) of a point on the edge of the shadow, (d) carrying out directional solidification or melting of melted material to a second time point (t1), (e) determining the lateral position change from at least one point, and (f) calculating the second melt height. In-situ determination of the current melt level during directional solidification or melting of at least partially molten material with volume leap during phase transition from solid to liquid in a crucible (4), comprises (a) determining first melt height (z0) of at least partially melted material at a first time point (t0), in which the melt height results from the distance from the bottom of the crucible to the molten surface of at least partially melted material, (b) producing a shadow or a bright spot on the molten surface of at least partially melted material at first time point (t0) by irradiation of at least one light beam from a light source (5), irradiating the light beam at an angle (alpha ) of greater than 0[deg] to less than 90[deg] to the surface of the melt (7), (c) determining the first position (x0) of at least one point on the edge of the shadow or bright spot with an optical detector (6), (d) carrying out directional solidification or melting of at least partially melted material to a second time point (t1), (e) determining the lateral position change (x0-x1 is equal to delta x) from at least one point with the optical detector, and (f) calculating the second melt height (z1) at second time (t1) by an equation comprising (z1 is equal to z0 + delta xx tan (alpha ). The position change in the direction of the light source is greater than 0, and the position change away from the light source is less than 0. At least one point laterally to the surface of melt at second time point (t1) has a second position (x1), which is moved to the first position (x0) in the direction of the light source or laterally away from the light source to the molten surface. The shadow or bright spot has an edge with multiple points. Independent claims are also included for: (1) in-situ controlled solidification or melting of at least one partially molten material with volume leap during the phase transition from solid to liquid in the crucible, comprising at least partially regulating the heating and/or cooling of the crucible by determining the change in melt height per time, preferably by the growth rate v(t) of the solid in the liquid melt, preferably by an equation comprising (v(t) is equal to delta z/delta t, where delta t is time interval for the change in melt height (delta z); (2) a device for determining the current melt level during directional solidification or melting of at least partially melted material with volume leap during phase transition from solid to liquid in the crucible comprising (a) at least one crucibles with the melt of at least partially melted material having volume leap during phase transition from solid to liquid, (b) at least one light source for irradiation of at least one light beam in at least one angle(alpha ) to the surface of the melt, (c) at least one optical detector for determining the lateral position change of point on the surface of the melt, and the converting lateral position change in a signal, (d) at least one unit, which converts the signal of the optical detector into the signal of the current melting height; and (3) a device for controlled solidification or melting of at least one partially molten material with volume leap during the phase transition from solid to liquid in the crucible, comprising at least one heating element and/or cooling element, which is regulated by the signal from the optical detector.